Field of the Invention
The present invention concerns a cooking appliance having a cooking space for receiving a product to be cooked. A cooling-air feeding device and a sensor module are provided for sensing an infrared radiation of a surface area of the product to be cooked or the interior of the cooking appliance.
Cooking appliances of the generic type allow the progress of the cooking process within a cooking space to be monitored on the basis of a contactless temperature measurement. This involves sensing the temperature of a surface area under measurement within the cooking space, that is to say for example the surface of the food prepared or a wall of the cooking appliance. Known for this purpose is the use of an infrared sensor, which however has to be protected against soiling and overheating to allow accuracy to be ensured. To achieve this, the infrared sensor is bathed in a cooling air flow. It is problematical that this is accompanied by simultaneous cooling of the monitored surface area under measurement and consequently may cause impairment of the cooking product and falsification of the measurement result. Published, Japanese Patent Application JP 08021631 A describes a microwave oven in which cool air is introduced into the oven and heated air is removed from the oven by a fan. The microwave oven is equipped with light sensors and bimetallic thermal elements that are disposed in front of the sensors and are cooled by the fan. In the event of operational malfunctions of the fan, the heating element or a temperature control device, the deformation of the bimetallic thermal elements resulting from the heating leads to a switching pulse in the light sensors and ultimately to switching off of the microwave oven. However, this configuration does not allow the progress of the cooking process to be ascertained. It is also not ruled out that the cooking product may be influenced by being exposed to the air supplied.
In the reference titled "Thermopile-IR-Sensormodul zur beruhrungs-losen Temperaturmessung in Haushaltsgeraten" [Thermopile-IR Sensor Module For Contactless Temperature Measurement In Domestic Appliances], J. Schiefendecker et al., Wiss. Z. techn. Univers. Dresden 43 (1994), issue 6, pages 41-44, a configuration of an infrared sensor module in the top wall of a microwave cooking space is described. In this case, a cooling air flow is conducted essentially parallel to the top wall. This makes it flow past an end wall of the infrared sensor module equipped with a protective filter. It is disadvantageous here, however, that the air flow causes vortices in the region of the protective filter and thereby contributes to the ingress of dirt particles. In addition, this type of air conduction is technically relatively complex.